At a posh press event in Manhattan’s Greenwich Village on Wednesday, freemium music subscription service Spotify revealed the “new direction” at which it has been hinting: a new API (application programming interface) that will let developers create apps that are powered by Spotify.

(In other words, we were right, for the most part.)

Spotify CEO Daniel Ek announced a few key details we did not foresee: These apps will be coded in fast, nimble HTML5, and they will live inside the Spotify app, so users don’t need to install any other standalone programs in order to use them. Developers can build the apps with “an easy to use Javascript API.”

Rolling Stone co-founder Jann Wenner was on hand to talk about how Spotify users can read about the bands they're listening to via Rolling Stone from within the Spotify app.

Spotify users can use these apps whether they pay for Spotify or not, said Ek. For now, Spotify’s developer partners do not share in Spotify’s revenue, but he also said these are still “early days” for the Spotify platform.

Ever since Spotify launched, said Ek, users have requested new features — everything from “DJ mode” to the ability to buy concert tickets. This strategy of outsourcing those new features to outside app developers makes a lot of sense from that point of view, because it allows Spotify to add a massive number of optional features that will be invisible to users who just want the vanilla version.

The new App Finder section in the left pane of the Spotify desktop app includes “editorial through Rolling Stone amongst others, concert tickets, lyrics, and many, many more experiences,” said Ek. The Rolling Stone app, he added (accompanied on stage by Rolling Stone co-founder Jann Wenner), is “really just the perfect companion to read about the stuff you want to hear as you hear it.”

Rolling Stone plans to tailor playlists and release them in Spotify. Other Spotify music platform launch partners plan to integrate music news, lyrics, sharing features, and other add-ons to Spotify’s App Finder.

Spotify CEO Daniel Ak announces Spotify's app-developing launch partners.

Here’s the complete list of partners at launch: Rolling Stone, Songkick, Last.fm, TuneWiki, The Guardian, Dagbladet, We Are Hunted, Soundrop, Top10, Billboard, Fuse, Gaffa, Pitchfork, ShareMyPlaylists, Tunigo, and MoodAgent.

In addition, Spotify is “eating its dogfood,” as the expression goes, by using its new API to add option features itself. One in-house Spotify app lets you see when your friends are starring songs, creating playlists, and so on. A single click on that user’s name lets you hear what they hear.

Before Wednesday’s event, a Spotify employee whose name we didn’t get said this would not be “a big announcement.” He clearly underestimates the power of the API — a somewhat geeky, structural concept that’s not as outright sexy as Spotify’s main allure: “Hey, look, free music!”

In this case, its function is to put Spotify’s over 15 million legally-licensed songs in the hands of app developers so they can freely create whatever apps they want out of that music. As Ek said, this will lead to a “burst of innovation.”

The tech news crew, including the author, turned out in full force to hear Spotify's announcement.

It might seem like the stuff of technology wonkery, or at least geekery or perhaps outright nerd-dom, but think about it: A kid coding away in a basement, anywhere in the world, should be able to build apps within the most popular music subscription service in the world. Want to play your friends’ Facebook preferences? Create a party playlist automatically based on the people attending? Tag songs to locations so that others can stumble across them? They’re working on it.

Even with Spotify’s previous API, derided as shoddy by some developers, developers cobbled together some of these ideas already. With Spotify’s revamped API, and the ability to include the apps within Spotify itself, the sky is the limit.

Spotify, the popular freemium music subscription service that emigrated to America in July, has attracted over 2.5 million paying subscribers, making it the most popular music subscription in the world. While it has encountered some turbulence of late, as some indie labels pulled their music due to what they considered too-low royalty payments, those labels might change their mind if the new Spotify platform takes off — otherwise, they won’t be part of this promising new ecosystem.

(Photos: Eliot Van Buskirk)